Color grading apparatus



May 15, 1945. w 0, BENNlNG 2,375,889

COLOR GRADING APPARATUS Filed Aug. 29, 1941 3 Sheets-Sheet 1- INVENTOR.

0r? firz'lle 07022323,; BY v .flifor May 15, 1945. w. Q BENMNG 2,375,889

COLORGRADING APPARATUS Filed Aug. 29, 1941 3 Sheets-Sheet 2 Tmq Y 3 6 Nb s iii-55'" 3 Sheets-Sheet 3 HIH'HI" Emi W. O. BENNING COLOR GRADING APPARATUS Filed Aug. 29, 1941 May 15, 1945.

Patented May 15, 1945 UNITED STATES PATENT OFFICE COLOR GRADING APPARATUS Wilbert Orville Benning, Los Angeles, Calif., as-

signor to Pacific Clay Products Company, a. corporation of California Application August 29, 1941, Serial No. 408,851

3 Claims.

employ a master tile in the apparatus at all times of the desired shade of color with which each tile is compared, while with the present invention the apparatus after being adjusted is operated without the use of a master or sample tile or other article, resulting in greater simplicity, speed, effectiveness and less labor in making comparisons. My invention thus dilfers from other devices designed for distinguishing differences in shade and color in as much as a single setting only is made in order to equalize the apparatus electrically as applied to a tile or other article known as a standard for its particular shade.

Among the objects of my invention is the production of an apparatus of its kind by which adjustments can be more easily made for making' comparisons of color and shade of tiles and other articles. Another object is the production of apparatus by which persons entirely unskilled in the matching of colors or in handling or operating mechanical or electrical apparatus can easily and efficiently operate the device. Another object of. this invention is greater simplicity of the component parts and the absence of optical systems, lenses, prisms and mirrors, as used between the initial light source and the tiles or other articles to be measured or compared. Another object is'the housing of the light sensitive cells in such a way that no extraneous light can influence their action or equalization, other than the tiles or articles under measurement or comparison. Among further objects is the production of an apparatus for the grading of shades or color wherein the human element of error is almost entirely eliminated when once the allowable tolerance has been set and in which the tiles or articles to be graded can be fed into registration with the light sensitive cell, manually or by slight modification, mechanically and automatically. A still further object is to provide a simple, accurate and dependable color or shade matching device, wherein a single source of substantially white light furnished With current from a battery source is utilized, thereby not influencing the light sensitive cells through a fluctuation of line voltage. With slight modification the present invention is readily adaptable to comparison of oils, paints, other liquids, powders, etc., as to their clarity, or intensity of color.

To these ends my invention comprises the features of construction and combination of parts hereinafter described and claimed.

In the accompanying drawings, forming part of this specification, Fig. 1 is a schematic view of my invention illustrating diagrammatically the elements employed and their cooperative functioning; Fig. 2 is a front elevation showing the structural application of the apparatus shown in Fig. 1, a portion of the cabinet being broken.

away; Fig. 3 is a side elevation of the structure shown in Fig. 2, a portion of the cabinet being broken away to expose part of the projection 'mechanism employed; Fig. 4 is an elevation of the instrument panel looking forward from within a portion of the cabinet, the latter being in section, the section being taken approximately on line l--4 of Fig. 3; Fig. 5 is a section of a detail taken approximately on line 5-5 of Fig. 4, showing the light sensitive cell regulating means employed for assisting in equalizing the electrical circuit; Fig. 6 is a typical section of a detail taken approximately on line 6-6 of Fig. 3; and

'7 is a plan of a detail showing the changeable filter element and the accompanying pilot light circuit for indicating the type of color screen in place for use, said circuit being shown diagrammatically.

In the following description it will be understood that changes can be made in the form, size, proportions and other details of construction, in order to adapt the invention to the individual requirements of the article or articles to be graded or sorted without sacrificing any of the ard tile or article is removed and one tile or article after another may be passed through the device in rapid succession without any other adjustment being made, all other operations being automatic or semi-automatic.

Two light sensitive cells B and C are employed which derive constant potential from battery 14 in circuit I5. Thiscircuit is coupled to the input of vacuum tube E. Tube E is used as an amplifier whose plate circuit I 6 feeds through the microammeter I3. Thus varying intensities of light are adapted to swing the grid of the tube E more or less negative which in turn increases or decreases the plate current of the tube and actuates the hand l2 of the micro-ammeter l3 to indicate any variations in shade from the standard. A single light source F in the form of an electric illuminating projection lamp, receiving current from the circuit I3 including battery I9 is inclined upwardly so as to maintain an unvarying and uniform intensity of illumination upon the surface of the tiles to be graded or measured exposed through light orifice In in the table II of the cabinet D. Preferably all nonfunctioning parts within the entire cabinet D are coated with a non-reflecting black pigment in order that any light rays that may reach the surfaces thereof will be absorbed and not refiected to impinge upon the light sensitive cells of the device. The direct reflection of light from surfaces of the tiles or articles to be graded or measured is avoided by allowing the light beams to strike each tile or article at such an angle that the directly reflected light does not impinge upon the light sensitive cell but is reflected upon the black absorbing walls of the interior of the case or cabinet.

Electrical resistivity means of modifying the sensitivity to any desired degree of tolerance and auxiliary means of equalizing the light sensitive cells by increase or decrease of light impinging directly upon cell C are employed. The resistivity means consists of a Vernier regulated potentiometer G which has two selector switches 29 and 2| in tandem on shaft 22, the switches containing fixed resistors 23 in parallel, across which is shunted a wire wound potentiometer coil 24. This combination provides an exceedingly fine adjustment of electric current conducted to the light sensitive cells to equalize them. The selector switch shaft 22 is journaled in the instrument panel 26 and is provided with a hand operable adjusting knob 25 on the face of the panel by which the seelctor switches are operated. The potentiometer vernier knob 21 which is carried by the potentiometer shaft 28 also is on the face of the panel (see Fig. 2). The potentiometer is of usual well known circular type having its coil arranged in a circle and its contact arm carried by the shaft 28. The knob is employed to revolve the shaft and its contact arm to regulate the vernier. The auxiliary means employed produces a rough approximation of the equalization of the light sensitive electric circuit, whereby the switches and potentiometer coil may function more effectively and consists of a source of light within variable focal range of the light sensitive cell C. This light is produced by an electric lamp 30 which is supplied with current by circuit l8 from battery l9, and is held by the carriage 3|. This carriage is guided vertically in the light proof housing 32. Cell C is mounted in a light shielding casing 33 which in turn is mounted upon and connected with the housing 32 by the opening 34 so that light emitted by lamp 3o affects the electric conductivity of said light sensitive cell for aiding in equalizing the light sensitive cells. The lamp is adjusted in distance from cell C by a shaft 35 which is in screw threaded engagement with the carriage and journaled in the housing. The upper end of the shaft has a bevel gear connection 36 with a hand operated transverse shaft 31, which latter is journaled in the instrument panel 26 and provided with a hand operated adjusting knob 38. Housing 32 is rigidly mounted on the inner face of the cabinet below said panel. In practice I have employed a one candle power lamp 3!]. The light effect of this lamp upon cell C varies with the square of the distance between the source of light and the cell and produces an effective equalizing medium. This medium acting on cell C and the medium afforded by the selector switches 20 and 2| including resistance 24 provide a very effective adjusting means for equalizing the photo-electric cells B and C.

Light from a single source and of unvarying strength (the lamp F) is cast at an obtuse angle upwardly through the orifice upon the down turned face of the standard tile A or other article and the light sensitive cell B is positioned exclusively in the direct focal range of the tile. Between the orifice and light sensitive cell a suitable filter element H is interposed for the purpose of narrowing the frequency band to substantially the same band as the articles to be sorted or graded.

The filter element comprises a horizontal filter l holding disk 40 rotatively mounted in a light and dust excluding housing 42 and shielded by a light baffle M. This housing is mounted upon the lower surface of the table H and is formed with a light passageway 43 through the housing and shield coaxial with or in vertical alignment with the orifice In in table H. The light sensitive cell B is held in a light and dust excluding container 44 which is secured to the lower surface of the housing 42 with said cell in the focal range of light cast upon the lower surface of the tile A or other article exposed through the orifice. The filter holding disk 40 contains a plurality of horizontal filter plates 45 of different colors (such as red, blue, green and daylight) arranged concentric to its axis and adapted to successively register with the passage 43 when the disk is turned. The filter disk is revolved by the flexible shaft 46 which leads to the back of the instrument panel 26, wherein it is journaled and connected to a hand operable knob 41 on the face of the panel. Thus the operator can easily'and quickly change the filters to match the type of color of tiles or articles which are to be compared or measured.

The projection lamp F for illuminating the surfaces of the tiles or other articles exposed through orifice H] is mounted by its enclosing shell 48 on the beveled wall 49 of the housing 42 so that a single light source reflected through the orifice is provided. The inner surfaces of the chamber within the housing 42 and shelf II are coated as above indicated with a light absorbing black pigment.

To facilitate feeding the articles to and removing them from the device a pair of conveyors 50 and 5| of usual type and parallel guide rails 52 on the surface of the table between which the tiles or articles to be graded or sorted pass into and out of registration with the orifice, are provided. Also to assist in excluding dust dirt and dampness from the housing a transparent plate. 53

is secured across the orifice it. The above arrangement for the selection of filters makes unnecessary handling and continually cleaning the delicate and easily damaged filter plates as they are completely protected from handling and the direct reflection of the rays of light from projection lamp F. Heretofore in other apparatus designed for a similar purpose wherein a filter is used the direct rays of light through a filter soon destroys the efficiency and accuracy of the filters by reason of fading. This objection is entirely overcome by my improved apparatus. The instrument thus can only measure light as seen through a filter and reflected from the tiles or articles being measured.

For the purpose of visually indicating to the operator which filter plate is interposed in the focal path between the light sensitive cell B and orifice ill, a bank of pilot lights 55 are provided on the instrument panel, one light of corresponding color being provided for each filter plate. These lights are connected in parallel with the battery circuit l8 and battery 19, each branch including an electric switch such as 56. The several switches (see Fig. '7) are grouped .around the periphery of the filter disk at spaced intervals corresponding with the filters. Each switch has a flexible switch arm normally held open by the disk but closing to illuminate a corresponding pilot light by entering a notch 58 in the periphery of the disk immediately when a companion filter plate is moved into juxtaposition with the light sensitive cell light passage 53.

The plate circuit 16 of the amplifier which receives its potential from battery 60 is connected with the micro-ammeter l3, whereby variations in current flow through the light sensitive cells B and C are connected to micro-ammeter l3, whose indicating hand it swings accordingly. The enlarged movement of this indicating hand I2 is projected by a beam of light and a pair of reflecting mirrors 6! and 62 onto a translucent screen I which is shown in the front face of the cabinet D immediately above the instrument panel 26, within convenient visual range of the operator. The translucent screen is divided into a number of various colored segments 63 (see Fig. 2), each of which corresponds to a different classification of shade for the particular color of tile or article being treated. Several difierent screens may be used by changing, each one of which may contain a different number of colored segments, depending on the number of shades into which tiles or articles are to be classified. The movement of the shadow of the micro-ammeter hand l2 which swings across this screen and which has been projected from said meter is multiplied. several times, thus enabling close comparisons. Colored divisions-in the screen make it easier for the operator of the device to separate the tiles or articles into their various classifications than it would be if letters or numbers were used for the same purpose.

The cabinet D is provided with a dark chamber 65 back of screen I in the lower portion of which is a supporting shelf 66 upon which a small projector lamp 61 is placed. This lamp and the microammeter are arranged in focal alignment on the shelf 50 as to project by a beam of light the shadow of the movement of the exposed meter hand through a set of adjustable projection lenses 68 (also held upon said shelf) onto the lower mirror 6!, which in turn reflects onto the upper mirror 62 and on again to the translucent screen I. The mirrors are thus supported and arranged in said chamber so as to reflect the movement of the indicating hand of the micro-ammeter onto the screen. The projector lamp receives its electric current supply from any convenient source.

Depending upon the wave length of the particular color of tile .or article to be measured, there is a difference in response by the light sensitive cells, the cells used in this instance approximating that of the normal human eye for color sensitivity and for this reason an adjustment for sensitivity is used in the plate circuit shunting the micro-amme'ter consisting of a potentiometer 69.

As shown, the cathode and grid of the amplifying tube E are connected to ground 10 through a selector switch 7! containing fixed resistors 12 of various suitable resistances for varying the bias. The shaft 13 of this switch is journaled' in and provided with an operating knob 14 on the face of the instrument panel 26.

Suitable manually operable switches 15 to 8 inclusive are provided for controlling the various circuits. These switches may be assembled upon the instrument panel 26 and operated by a sinle bar 8! for simultaneous operation.

In general to operate the apparatus, the projection lamp 61 is operated by turning on the controlling switch 82 and the bar switch 8| is moved to the position marked On, whereby energizing current is supplied to the amplifying tube E, the light sensitive cells B and. C, the filter pilot lights 55 and the light regulating lamp 30 for the light sensitive cell C. This adjustable lamp 3!! in housing 32 below thelight sensitive cell C roughly approximates the equalizing effect of cells B and C after the standard tile or article has been placed over orifice I0. Itrequires several minutes to bring the control operating temperature to the amplifying tube when starting the device. Following this operation the standard such as tile A is placed face down in proper position between the guide rails 52 and directly over orifice I!) in the table I I. The back of a standard tile, which may contain the printed directions for the necessary setting of the device is now facing the operator who merely'carries out the directions printed thereon. For instance, the next step would be to turn control knob 41 which would rotate filter assembly H until the proper filter for the particular tile or article being compared is in alignment with the light sensitive cell B and tile A. When align ment is correct a pilot lamp such as 55 of 'a like color is illuminated on the panel. This arrange ment for the selection of filters makes unnecessary the handling of or the necessity for continually cleaning the delicatefilters, as they are placed in a rotating disk protected from the direct reflection of the rays of light from lamp F by the shield M, and also protected from dust and dirt by a light proof housing 42. The light sensitive cell 23 is protected against any dust, dirt or extraneous lightby housing 44, and can only vary in proportion to the light as seen through filter 45 and coming only from the tile A or article to be compared. It is'impossi-ble for any extraneone light from any source other than that intended to ever reach the light sensitive cell B. Now that the standard tile or article is in place and the proper filter has been selected the knob 25 is turned to adjust the selector switch G for roughly equalizing the electric circuit containing the light sensitive cells. A still further and .finer adjustment between the cells is obtained by regulating the vernier potentiometer 24 through the turning of the vernier adjustin knob 21 until finally the image or shadow of the micro-ammeter indicating hand I2 is centered on the scale as a reference during the further operation of the device. Now the standard tile or article can be removed from the apparatus and the unknown tiles or articles can be started moving across the orifice previously occupied -by the standard. Since the comparison readings from now on are almost instantaneous a very rapid form of comparison suited to quantity production is made possible.

The structure itself of the unit supporting the lamp illuminating the tiles or articles under comparison, the filter assembly H, individual switches 56 indicating by means of pilot lamps 55 located on panel 26, and the supporting dust proof and extraneous light proof housing for light sensitive cell B, is of distinct advantage inasmuch as the design of the structure permits of a much greater degree of sensitivity due to the compactness and nearness of all associated parts. Especially the short distance between the illuminating lamp F and the tiles or article being illuminated through orifice II] in the table II, and the short distance between the tiles or articles illuminated and the light sensitive cell B, which is directly below said orifice increase the sensitivity of the apparatus. Also the arrangement of the filter assembly which -is interposed between the tiles or articles illuminated and said light sensitive cell B in the housing and protected by the light baiiie 4| assists in producing increased efiiciency of operation. Heretofore, in other apparatus designed for a similar purpose, wherein a filter is used, the direct or specularly reflected rays of light through a filter soon tend to destroy the efficiency and accuracy of the device for comparison or measurement purposes due to the fading of said filters. This objection is overcome by my improvement.

It has been usual to measure or compare the unknown by replacing it with the "standard and the difference in adjustment of equipment each time this replacement is made indicating possible difference in shade or color, makes this method laborious and unsuited to quantity production. By the use of my improved apparatus this objection is also overcome, and a saving of time and labor is effected.

In accordance with the patent statutes, I have described the principles of operation of my invention together with the apparatus which I now consider to represent the'be'st embodiment thereof, but I desire to have it understood that the construction shown is only illustrative and that the invention can be carried out by other means and applied to uses other thanthose above set forth within the spirit of the invention and within the scope of the following claims.

I claim: I

l. A color and shade comparison apparatus, comprising, a table having an exposure orifice, an instrument panel at the back of said table, a light excluding enclosure below said orifice, a main light sensitive cell in said enclosure positioned in alignment with said orifice, a light source of constant intensity arranged in said enclosure at an acute angle to said orifice to cast a steady beam upon the surface of an article displayed through said orifice whereby said cell receives'only difiusely reflected rays, a carrier for moving a succession of articles into registration with said orifice, an electrical circuit in which said light sensitive cell is included, a compensatin light sensitive cell in series with said main light sensitive cell in said circuit, a filter holder disk rotatable in said light excluding enclosure having a plurality of filters of different colors adapted to be successively interposed by rotation of the disk in the light path between said orifice and said main light sensitive cell, manually operable means for rotating said disk to bring its filters successively into said light path, a lamp of constant intensity in alignment with said compensating cell and movable to vary the distance between the lamp and said compensating cell to vary the resistance of said cell, variable resistance means for controlling the fiow of current through the circuit containing said main cell and said compensating sensitive cell, a screen supported by said panel having a band of difierent colors, an indicator cooperating with said band and infiuenced by the current fiow through the cell circuit to indicate color and shade variations of articles positioned over said orifice, a bank of electrically illuminated different colored pilot lights mounted in said panel and included in an energizing circuit, said light colors corresponding substantially with the colors of said filters in said disk, and a switch in said energizing circuit controlling the current for each of said pilot lights, said disk having means for automatically closing the switch controlling the pilot light corresponding with the filter which is moved into the light path between said orifice and the main light sensitive cell.

2. Color and shade comparison apparatus, comprising, a table having an exposure orifice, an instrument panel at the back of said table, a light excluding enclosure below said orifice, a main light sensitive cell in said enclosure in alignment with said orifice, a light source of substantially constant intensity in said enclosure obscured from said cell and arranged to cast a steady beam of light at an acute angle upon the surface of an article displayed through said orifice whereby the cell receives only difiusely reflected rays, a carrier for moving articles successively into registration with said orifice, an electrical energizing circuit in which said light sensitive cell is included, a compensating light sensitive cell in series with the main light sensitive cell in said circuit, a filter disk holder rotatable in said enclosure having a plurality of filters of difierent colors adapted to be successively interposed between said orifice and said main light sensitive cell through the revolution of said holder, a light baflie shielding the filters not interposed between said orifice and main light sensitive cell, manually operable means for rotating said filter holder to move its filters successively into complete registration with said orifice, a lamp of constant intensity movable to vary the resistance of the compensating cell in the energizing circuit and thereby vary the current traversing the energizing circuit containing the main light sensitive cell, variable resistance means connected in parallel with the cell circuit, a screen supported by said panel having a band of different colors, an indicator cooperating with said band and varied by the current traversing the cell circuit to indicate color and shade vari ations of articles positioned over said orifice, a bank of electrically illuminated pilot lamps .in an energizing circuit, said lamps eing of Colors corresponding substantially with the colors of said filters in said disk, and a series of switches in said energizing circuit actuated by engaging means in the periphery of said disk as the latter is revolved for energizing said pilot lamps and adapted to close the circuit including a pilot lamp corresponding in color with that of the filter in registration with said orifice.

3. Color and shade comparison apparatus,

comprising, a table having an exposure orifice, a light excluding enclosure below said orifice, a main light sensitive cell in said enclosure in alignment with said orifice, a light source of constant intensity arranged at an acute angle to said orifice to cast a steady beam upon the surface of an article displayed through said orifice whereby said cell receives only diffusely reflected rays, an energizing electrical circuit in which said light sensitive cell is included, a filter disk holder rotatable in said light excluding enclosure having a plurality of filters of difierent colors adapted tobe successively interposed between said orifice and said main light sensitive cell by the rotation of said holder, manually operable means for rotating said holder, means connected in series with the main light sensitive cell for regulating the resistance of said circuit, pilot lights of colors corresponding with the color fil-- ters in said filter disk holder, switches corresponding in number with the filters in said filter disk holder connected in an energizing circuit with the pilot lights, and means actuated by the rotation of the filter disk holder adapted to actuate a switch corresponding with the filter which is exposed between the main light sensitive cell and said orifice and cause the energizing of the pilot light of a color corresponding with the color of the exposed filter.

WILBERT ORVILLE BENNING. 

